Spot adjusting mechanism for radio transmitters



June 29, 1943. v H. J. H. WASSE LL 2,323,170

SPOT ADJUSTING MECHANISM FOR RADIO TRANSMITTERS I Filed April 1, 1941INVENTOR HAROLD WASSELL ATTORNEY Patented June 29, 1943 SPOT ADJUSTINGMECHANISM FOR RADIO TRANSMITTERS Harold Joseph Hughes Wassell,Chelmsford, England, assignor to Radio Corporation of America, acorporation of Delaware Application April 1, 1941, Serial No. 386,322 7In Great Britain April 3, 1940 12 Claims.

The present invention relates to improvements in spot adjustingmechanism. Examples of such use are so-called spot-wave selectingmechanism in radio transmitters, wherein it is desired automatically toadjust the transmitter to transmit any one of a plurality ofpredetermined frequencies. The invention is not, however, so limited.

According to the invention, a spot-adjusting mechanism comprises arotatable shaft which is coupled to a device to be adjusted, a pluralityof stop-cams mounted on and rotatable with said shaft, said cams beingrelatively angularly displaced in accordance with differentstop-positions, a like plurality of pivoted'levers, one for eachstop-cam and lying in the path of travel thereof, a draw-rod for eachlever, means operable upon said draw-rods whereby to pull said leversout of the path of travel of said stopcams, and selector meansassociated with said draw-rods whereby to prevent one of said drawrodsfrom pulling its associated lever from the path of one of saidstop-cams, the arrangement being such that upon operation of saidselector means, all levers but a selected one are withdrawn from thepaths of all but a selected stopcam, and the rotatable shaft may be setinto rotation and continued until stopped by said last mentionedstopcam. r

In one way of carrying the invention into efiect, as illustrated in theaccompanying drawing, in which:

Fig. 1 is a perspective view of the general arrangement; and Y Fig. 2 isan end elevation showing one of the selecting magnets and armatures.

Referring now to the drawing: there is mounted upon a frame R. a motor0, which is coupled to a rotatable shaft V. A plurality of stop-arms orcams A, are separately secured and so adjusted as to be able to occupydifferent relative angular positions in accordance with predeterminedrequirements and to be fixed in these positions. These stop-cams may, asshown, comprise fiat snail-shaped plates. Also mounted on or associatedwith the shaft is a member or members of a device, the position of whichis to-be adjusted. It or they may be the rotor or rotors of anadjustable condenser or of adjustable condensers. The shaft is flexiblycoupled as by a slipping clutch indicated at F to the driving motor insuch a manner that the motor may drive the shaft unless the movement ofthe latter is positively prevented, when the flexible coupling willslip.

Mounted upon a common fixed pivot U, which is situated at a shortdistance from and is parallel to the shaft V on frame R, is a number oflevers of shallow U-shape, one for and lying in the path of eachstop-cam A. The pivot extends through the end of one arm of the U-shapedlevers and there are provided on the end of the other arm, two pivoteddiscs C and C, the periphery of one disc C extending beyond the outsideof the arm and that of the other disc extending into the cup of theU-shaped lever. The pivots of these two discs C and C and the fixedpivot U on which the levers are mounted are all situated in asubstantially straight line. Fixed to frame R and situated within thearms of the LI -shaped levers is a common stop thrust member D whichjust engages the periphery of the inner disc C of all levers B when thelatter are in their upper positions, thereby to take up any thrustimparted by the stop-cams A to the levers B and thus to prevent thrustof the levers upon their pivot U. The levers B are maintained in theirupper positions by means of springs mounted, for example, upon thecommon fixed pivot U. These springs are not shown in the drawing.

Pivotally attached to each one of the free ends of the U-shaped pivotedlevers is a draw-rod E to the remote ends of which is attached aretracting spring Q attached to the fixed frame R of the apparatus whichtends to draw the draw-' rod E down and thus to move the lever B towhich it is attached out of the path of the stopcam A with which thesaid lever is associated. A short bracket G extends horizontally fromeach drawn-rod and rests upon one arm of a bellcrank lever H wherebydownward movementof said draw-rods is prevented unless otherwisepermitted.

Mounted upon a fixed pivot W, situated at a convenient distance from andparallel to the plane in which the draw-rods E lie, are a number ofbell-crank levers H, each having one arm extending under the saidbracket G whichex tends from a draw-rod, so that the bracket rests onsaid arm. The other arm of each bell-crank lever H extends downwardsfrom the fixed pivot shaped levers B. It also, in this position,displaces all selector-bars I to the left.

Each selector-bar has a catch J punched out from the side of it.

Associated with each selector-bar and mounted on frame R is anelectro-magnet S, only one of which is shown, and each electro-magnet Sis provided with an armature X to which is attached a resilient tongueT. The resilient tongue T which may be in the form of a loop spring Tlof each electro-magnet S is located just to the right of, and cooperateswith the catch J on the associated selector-bar I in such manner asshown by Fig. 2 to prevent, when the electromagnet is energized,movement in an outward direction (that is a direction to the right, inthe drawing, such as to permit retraction of the associated draw-rod) ofthe selector-bar. This is accomplished by tongue T being drawn in towardthe side of the selector-bar I when the electromagnet S is energized.

- Power for driving them may be applied to the adjustable shaft V andthe cam-drum L in any convenient manner, but such power is appliedeither through the intermediary of an energized electro-magnet S or incommon with the energization of such magnet, through the intermediary ofastarting mechanism, such as, for example, a selector switch K, which isconnectedln' series with a source of current M and each"electric-magnet: circuit SI to S1, inclusive.

. The-sequence'o'f. operations is as follows:

. An electromagnet S, appropriate to a" desired spot-position of theadjustable shaft V, is energized: by placing switch K in a desiredposition, and, attracting its. armature. X, brings the resilienttongue Tcloseto and into the'path of the catch J on a selector bar I. Thecam-drum then commences to rotate and the cam, passing through its peakposition, as shown, allows the horizontal arms of all the; bellcranklevers .H which until now are. all in substantially their upperpositions) to fall. The horizontal arm of thatbell-crank lever Happropriate to the desired stop position cannot fall, however, by reasonof r the catch J on the selector bar I associated with it, engaging theresilient, tongue T, .on therarmatureX of the energized electromagnet S.The falling of the horizontal: arms of the bell-crank1QYQIfShH:-lS'-3iSvSiS'ted' by; theretracting springs Q associatedwiththe draw -rodsE which, asstated; haveqattached to-them brackets Gresting upon the horizontal arms; of the I bell crank levers H. Atlabout the time that drive is applied to the cam-drum L, drive is also.applied to ,thegadjust retracting springs Q. The draw-rods E whendrawndown remove the ends of the U-shapedleverso-l3 from the paths ofthe stop-cams A so freeing the shaft V which may now rotate until thestop-cam A appropriate to a desired stop position engages the U-shapedlever B also appro priate to that position, which lever will not have.

been removed from the path'of the saidstopcam. When thesaidstop-cam-engages-the said U-shaped lever, further rotation of theadjustable shaft is arrested, the drive being withdrawn by reason ofslip in the flexible coupling F. Ro-

tation of the cam-drum and of the moving members of the flexiblecoupling continues until a predetermined selection cycle is completed,when the motor is switched off by switch K. The camdrum will then be inposition somewhat before its peak position.

What is claimed is:

1. A spot-adjusting mechanism for adjusting a device comprising arotatable shaft coupled to said device to be adjusted, means forrotating said shaft, a plurality of stop-cams mounted on and rotatablewith said shaft, said cams being relatively angularly displaced indilferent predetermined stop-positions, a like plurality of pivotedlevers,'one for each stop-cam and lying in the path of travel thereof, adraw-rod for each lever, means operable upon said draw-rods to pull saidlevers out of the path of travel of said stop-cams, and selector meansassociated with each one of said draw-rods to prevent one of saiddraw-rods from pulling its associated lever from the path of one of saidstop-cams, the arrangement being such that upon operation of saidselector means, all levers are withdrawn from the paths of all but oneselected lever and a corresponding stop-cam, and the rotatable shaft isset into rotation and so continued until stopped by said last mentionedstop-cam.

2. A mechanism" as claimed in claim 1 wherein there is also mounted onsaid rotatable shaft the rotor of an adjustable condenser.

3. A selecting mechanism for adjusting a de vice comprising a rotatableshaft coupled to said device to be adjusted, a rotatable device forrotating said shaft, a plurality of stop cams mounted-on and rotatablewith said shaft, said cams'being relatively angularly displaced indiiferent predetermined stop positions, a like plurality of pivotedlevers, one for each one of said stop cams and lying in the path oftravel thereof, flexible coupling means interposed between said shaftand said rotatable device to allow slippage when motion on one of saidstop-cams is prevented, a draw rod for each lever, means operable uponsaid draw-rods topull said levers out of the path of travel of said stopcams, and selector means associatedwith each one of said draw-rods toprevent one of said draw-rods from pulling its associated lever from thepath of one of said stop cams, the arrangement being such that uponoperation" of said selector means, all levers are withdrawn from thepaths of all but one selected lever and a corresponding stop cam; andthe rotatable shaft is set into rotationand so continued until stoppedby said last-mentioned stop cam..

4.- A selecting mechanism for adjusting a device comprising a rotatableshaft coupled to said device tobe adjusted, a-rotatable device for ro-'tating said shaft, a plurality of stop cams mounted on and rotatablewith'said shaft, said stop cams being relatively angularly displaced indifferent predetermined stop positions, a like plurality 0f pivotedlevers, one for each one of said stop cams and lying in the path oftravel thereof; flexible coupling means interposed between said shaftand said rotatable device to allow slippage when motion on one ofsaid'stop cams is prevented, alike plurality of shallow U-shaped levers,one for each one of said stop cams, said U-shaped leversbeing mounted ashort distancefrbr'ri, and parallel to, said rotatable shaft; and in thepath of each stop cam, a draw-rod for each lever, means operable uponsaid draw-rods to pullsaid levers out of the path of travel ofsaid stopcams, and selector means associated with each one of said draw-rods toprevent one of said draw-rods from pulling its associated lever from thepath of one of said stop cams, the arrangement being such that uponoperation of said selector means, all levers are withdrawn from thepaths of all but one selected lever and a corresponding stop cam, andthe rotatable shaft is set into rotation and so continued until stoppedby said last-mentioned stop cam.

5. A selecting mechanism for adjusting a de vice comprising a rotatableshaft coupled to said device to be adjusted, a rotatable device forrotating said shaft, a plurality of stop cams mounted on and rotatablewith said shaft, said stop cams being relatively angularly displaced indifferent predetermined stop positions, a like plurality of pivotedlevers, one for each one of said stop cams and lying in the path oftravel thereof, a flexible. coupling means interposed between said shaftand said rotatable device to allow slippage when motion on one of saidcams is prevented, a like plurality of shallow U-shaped means operableupon said draw-rods to pull said levers out of the path of travel ofsaid stop cams, and selector means associated with each one of saiddraw-rods to prevent one of said draw-rods from pulling its associatedlever from the path of one of said stop cams, the arrangement being suchthat upon operation of said selector means, all levers are withdrawnfrom the paths of all but one selected lever and a corresponding stopcam, and the rotatable shaft is set into rotation and so continued untilstopped by said last-mentioned stop cam. V

6. A selecting mechanism for adjusting a dc Iii) vice comprising arotatable shaft coupled to said device to be adjusted, a rotatabledevice for rotating said shaft, a plurality of stop cams mounted on androtatable with said shaft, said stop cams being relatively angularlydisplaced in different predetermined stop positions, a like plurality ofpivoted levers, one for each one of said stop cams-and lying in the pathof travel thereof, flexible coupling means interposed between said shaftand said rotatable device to allow s1ippage when motion on one of saidstop cams is prevented, a like plurality of shallow U-shaped levershaving two arm portions, two pivoted discs for each arm of said level,the periphery of one disc extending beyond the outside of the arm andthat of the other disc extending into the cup portion of said U-shapedlever, the pivots of each one of said discs and the pivot on which theU-shaped levers are mounted, being all situated in a substantiallystraight line and in the path of each stop cam, a common member engagingthe periphery of the inner disc of all of said levers in their upperportions to take up any thrust imparted by said stop cams to the levers,and thus to prevent thrust of the levers upon their pivot, a pluralityof springs mounted upon acommon pivot for maintaining said levers intheir upper portions, a draw-rod for each lever,

means operable upon said draw-rods to pull said levjers out of the pathof travel of said stop cams, and selector means associated with each oneof said draw-rods to prevent one of said draw-rods from pulling itsassociated lever from the path of one of said stop cams, the arrangementbe,- ing such that upon operation of said selector means, all levers arewithdrawn from the paths of all but one selected, lever and acorresponding stop cam, and the rotatable shaft is set into rotation andso continued until stopped by said last-mentioned stop cam.

7. A selecting mechanism. for adjusting a device comprising a rotatableshaft coupled to said device to be adjusted, a rotatable device forrotating said shaft, a plurality of stop cams mounted on and rotatablewith said shaft, said cams being relatively angularly displaced indifferent predetermined stop positions, a likeplurality of pivotedlevers, one for each one of said stop camsand lying in the path oftravel thereof, ilexiblecoupling means interposed between said shaft andsaid rotatable device to allow slippage when motion on-one of said stopcams is prevented, a like plurality of shallow U-shaped levers havingtwov arm portions, two pivoted discs for each arm of said lever, theperiphery of one disc extending beyond the outside of the arm and thatof the other disc extending into the cup portion of said U-shaped lever,the pivots of each one of said discs and the pivot on which the U-shapedlevers are mounted, being all situated in a substantially straight lineand in thepath of each stop cam, a common member engaging the peripheryof the inner disc of all of said levers in their upper portions to takeup any thrust imparted by said stop cams to the levers, and thus toprevent thrust of the levers upon their pivot, a plurality of springsmounted upon a common pivot for maintaining said levers in their upperportions, a draw-rod for each lever, means operable upon said draw-rodsto pull said levers out of the path of travel of said stop cams, saiddraw-rod pivotally attached to the free ends of the U-shaped pivotedlever, a retracting spring attached to the frame of the apparatus todraw said draw-rod down and thus to move the lever to which it isattached out of the path of said stop cam to which said lever isassociated, and selector means associated with each one of saiddraw-rods to prevent one of said draw-rods from pulling its associatedlever from the path of one of said stop cams, the arrangement being suchthat upon operation of said selector means, all

, levers are withdrawn from the path of all but one selected lever,v anda corresponding stop cam, and the rotatable shaft is set in rotation andso continued by said last-mentioned stop: cam.

8. A radio transmitter selecting mechanism for adjusting a devicecomprising a rotatable shaft coupled to said device to be adjusted, arotatable device for rotating said shaft, a plurality of stop.

cams'mounted on and rotatable with said shaft, said stop cams beingrelatively angularly displaced in different predetermined stop position,a like plurality of pivoted levers, one for each one of, said stop camsand lying in the path of travel thereof, flexible coupling meansinterposed between said shaft and said rotatable device to allowslippage when motion on one of said stop cams is prevented, a draw-rodfor each lever, means operable upon said draw-rods to pull said leversout of the path of travel of said stop cams, a bell crank lever, linkedto each one of said drawrods, a short bracket extending horizontally outfrom each one of said draw-rods, and resting upon one arm of said bellcrank lever, whereby downward movement of said draw-rods is prevented,unless otherwise permitted by said short bracket, and selector meansassociated with each one of said draw-rods to prevent one of saiddraw-rods from pulling its associated lever from the path of one of saidstop cams, the arrangement being such that upon operation of saidselector means, all levers are withdrawn from the paths of all but oneselected lever and a corresponding stop cam, and the rotatable shaft isset into rotation and so continued until stopped by said last-mentionedstop cam.

9. A selecting mechanism for adjusting a device comprising a rotatableshaft coupled to said device to be adjusted, a rotatable device forrotating said shaft, a plurality of stop cams mounted on and rotatablewith said shaft, said stop cams being relatively angularly displaced indifferent predetermined stop positions, a like plurality of pivotedlevers, one for each one of said stop cams and lying in the path oftravel thereof, flexible coupling means interposed between said shaftand said rotatable device to allow slippage when motion on one of saidstop cams is prevented, a draw-rod for each lever, means operable uponsaid draw-rods to pull said levers out of the path of travel of saidstop cams, a bell crank lever linked to each one of said draw-rods, ashort bracket extending horizontally out from each one of said draw-rodsand resting upon one arm of said bell crank lever, a pivot situated at aconvenient distance from, and parallel to, the plane at which saiddraw-rods lie, each one of said bell crank levers having one armextending under said brackets which extend from a draw-rod, so that thebracket rests upon said arm, the other arm of each bell crank leverextending downwards from the pivot and its extreme end being attached toa selector bar adapted to slide horizontally under the action of saidbell crank lever, and selector means associated with each one of saiddraw-rods to prevent one of said draw-rods from pulling its associatedlever from the path of one of said stop cams, the arrangement being suchthat upon operation of said selector means, all levers are withdrawnfrom the paths of all but one selected lever and a corresponding stopcam, and the rotatable shaft is set into rotation and so continued untilstopped by said last-mentioned stop cam.

A se ec m ha ism o d usti a device comprising a rotatable shaft coupledto said device to be adjusted, a rotatable device for rotating saidshaft, a plurality of stop cams mounted on and rotatable with saidshaft, said stop earns being relatively angularly displaced in differentprede m ne st posi ons, a ke p u i y of pivoted levers, one for each oneof said stop cams and lying in the path of travel thereof, flexiblecoupling means interposed between said shaft and said rotatable deviceto allow slippage when motion on one of said stop cams is prevented, a

draw-rod for each lever, means operable upon said draw-rods to pull saidlevers out of the path of, travel of said stop cams, a bell crank leverlinked to each one of said draw-rods, a short bracket extendinghorizontally out from each one of said draw-rods and resting upon onearm of said bell crank lever, a pivot situated at a convenient distancefrom, and parallel to, the plane at which said draw-rods lie, each oneof said bell crank levers having one arm extending under said bracketswhich extend from a draw-rod, so that the bracket rests upon said arm,the other arm of each bell crank lever extending downwards from thepivot and its extreme end bein attached to a selector bar adapted toslide horizontally under the action of said bell crank lever, a cam-drumarranged so that in its peak position all of the said horizontal armportions of each one of said bell crank levers, and with them all ofsaid draw-rods and U-shaped levers, are raised, in which position allsaid selector bars are displaced, and selector means associated witheach one of said draw-rods to prevent one of said draw-rods from pullingits associated lever from the path of one of said stop cams, thearrangement being such that upon operation of said selector means, alllevers are withdrawn from the paths of all but one selected lever and acorresponding stop cam, and the rotatable shaft is set into rotation andso continued until stopped by said last-mentioned stop cam.

11. A selecting mechanism for adjusting a device comprising a rotatableshaft coupled to said device to be adjusted, a rotatable device forrotating' said shaft, a plurality of stop cams mounted on and rotatablewith said shaft, said stop cams being relatively angularly displaced indifferent predetermined stop positions, a like plurality of pivotedlevers, one for each one of said stop cams and lying in the path oftravel thereof, flexible coupling means interposed be' tween said shaftand said rotatable device to allow slippage when motion on one of saidstop cams is prevented, a draw-rod for each lever, means operable uponsaid draw-rods to pull said levers out of the path of travel of saidstop cams, a bell crank lever linked to each one of said draw-rods, ashort bracket extending horizontally out from each one of said draw-rodsand resting upon one arm of said bell crank lever, a pivot situated at aconvenient distance from, and parallel to, th plane at which saiddrawrods lie, each one of said bell crank levers having one armextendingunder said brackets which extend from a draw-rod, so that the bracketrests upon said arm, the other arm of each bell crank lever extendingdownwards from the pivot and its extrme end being attached to a selectorbar adapted to slide horizontally under the action of said bell cranklever, a cam-drum arranged so that in its peak position all of the saidhorizontal arm portions of each one of said bell crank levers, and withthem all of said draw-rods and U-shaped levers, are raised, in whichposition all said selector bars are displaced, selector means includingan electro-magnet for each selector-bar, each one of saidelectro-magnets being provided with an, armature, a resilient tongueattached to said armature, said resilient tongu cooperating with eachelectro-magnet, a c tch associated with said selector-bar in such amanner as to prevent movement in an outward direction when one of saidelectro-magnets is energized, such as to permit retraction of theassociated draw-rod of the selector-bar, whereby all of said levers arewithdrawn from the paths of all but one lever, and a corresponding stopcam, and the rotatable shaft is set in rotation, and so continued untilstopped by said last-mentioned stop cam.

12. In a mechanism for a radio device, the position of which is to beadjusted, a plurality of cams capable of being adjusted in differentpredetermined angular positions, a rotatable shaft on which said camsare mounted, said shaft coupled to said device, a plurality of linkages,each one of which is adapted to be actuated by each one of said cams andlocated in a corresponding position thereto, means for selecting andcontrolling the position of one of said linkages, a cam-drum for movingthe position of all of said linkages, means for rotating said shaft andsaid cam-drum simultaneously, and means located on each one of saidlinkages whereby a desired position of said device is secured by aselected cam and its corresponding linkage being retained in a stopposition when a predetedmined position is selected by said selectingmeans.

HAROLD JOSEPH HUGHES WASSELL.

